Experimental design
In Mid-August of 2021, field data were collected in two sites of the
Tibetan semi-arid alpine steppe, Shrub encroachment has been prevalent
in both the two sites, with one site encroached by a
leguminous shrub (C.
spinifera ) and the other site encroached by an
none-leguminous shrub (D.
fruticosa ). At each site, alpine steppe and shrub encroached alpine
steppe were selected (Fig. 1a-d). At each of the AS and
ASSE treatments, a 30 m × 30 m grassland plot was set,
with the paired grassland plot and shrub encroached grassland plot
separated by approximately 30 m. Within each plot, five 0.5 m × 0.5 m
quadrats were sampled. Totally, 20 quadrats (2 shrub types × 10
quadrats) were sampled.